Process for preparing allyl esters of carboxylic acids



the use oi the generally cheliper aiiylic halides instead of the allylicalcohols and yields esters which are sub- United hnteniod June if, 396%2,939,379. stsntiaily colorless, thus eliminating extensive purificationI procedures. Further, the esterification is accomplished PmwEss FORPREPARING Esmm 5 in much shorter periods oi time than is generallyrequired CAREQXYLW p for the conventional acid cntslymd acid-alcoholestcrifi- Aide De Eenedictio Eei'heiey, Csih'it, sissignor to @hell whenP L Oil Company, .a corporation oi Dsln As noted above, the esters areprepared according to the present process by reacting an alkali salt ofthe organic carboxyiic acid with on allylic halide in an argue .ousmedium under critical pH control. if the acid is a poiycarboriylic acid,the salts may be a complete salt, i.e. one wherein all of the carbonylgroups have been converted to salt groups, or it may be a salt of apartial ester of the poiycarboitylic acids with any type monohydric al-No Drawing. Filed Feb. 7, 1957, Sea", Noe 638,697

This invention relates to a new process for preparing unsaturatedcsters.More particularly, the invention recohol. Thus, for example the salt maybe disodiam latcs to an improved process for preparmgbetmgamma-Phthalate or may be sodium any} phthalate. ethglcnically unsaturatedesters of organic carboxylic The acids whoS8 Sodium salts are employedin the ass of the present invention maybe any organic acid.

m lq l yi P15113109 1 3: 3 a new a fi These acids may be aliphatic,cycloaliphatic, aromatic or e 6169' Pmcess Preparing e agamma'e Y emca Yheteroc clic and me be saturated or unsaturated. They unsaturated estersof organic carboxylic acids which corn may g be mom) 2,, polycarboxylicacids and may be P heating alkali meta f of h i with a beta substitutedwith a variety of different substituents, such gani nacthylenicallyunsaturated halide in an aqu o ssalkyl radicals, ether radicals and thelike Examples medium and adding an alkaline material to the reactionopthe am}? mclvude, amfmg 9mg: acme acid mixture as to mamtam the PH thef f mixture acid, butyric acid, acrylic acid, adipic acid, succinicacid, throughout the course of the reaction within the range of benzoicacid, cyclohexanoic acid, tert-butylcyclohexanoic 6.0 to 8.0 and thenrecovering the desired ester from the acid, toiuic acid,p-tert-butylbenzoic acid, 3,5-ditertiaryreaction butylbenzoic acid,pyromeliitic acid, orthophthalic acid,

As e s? emimdmfemi the Provides a isophthalic acid, terephathalic acid,diphenyl-4,4'-dicarmethod focma nng diallylic phthalates which comprisesb fi acid, dicarbnxydiphenylmethaney dicarboxy, heating a disod um saltof n phthalic acid with an allylic phmylmlylmahane, 3 MhydrmqhlAbanzenedicarboxvlic halide in an aqueous medium and then addingalkaline acid 4 butyl 1l3 benzenedicarboxyfic acid, s isopmpyl materialto the reaction mixture so as to maintain the pH l'4 benzenedicarboxyiicacid P f d acids are the 0f the 'f at about mononuclear aromaticdicarboxylic acids containing from Allylic esters such as diallylphthalate, have been found 8 to 16 Carbon atoms m pal'ilculafil usefulthe Preparation f resms and Examples of suitable salts of the aboveacids include, plastics. These esters, however, have been round to beamong others, smdium acetate, Sodium butymte: sodium dimwk QP P j Themniefitlomfl and benzoate, potassium cyclohexanecarboxylate, disodiumcatalyze? esterlficaum f the acid anhydndefvlth the phthalate, sodiumallyl phthalate, sodium methallyl isoalcohol is troublesome in that theesters are discolored phthalate sodium ethauyl tel-ephathalateii-potassium and the yields obtained in the reaction and purificationterephthalme disodium salt of 3 eflqyf l,4 benzenedicar procedures arehas suggeist,ed the boxylic acid, sodium allyl S-isopropyl-l,t-benzenedicaresters be prepared by reacting the acid anhydride with anbow/late Sodium ethyl phthalaie and sodium m allylic halide, but theconversions obtained by this method w phthalate' have been littlebetter-than those obtained with the con- The salts of these acids may beprepared by any Sum ventional acid catalyzed acid-alcohol esterificationprocable method, such as by treating the acid, or the partial ester ofthe acid, with an appropriate quantity of an aque- It is therefore an obect of the invention to provide a Gus solution of a sodium or potassiumbase or salt such w Pmce5 prepafmg unsaturated esters' It a as sodiumhydroxide. The salts of the aromatic acids further ob ect to provide anew method for prcp g may be removed from the resulting aqueous solutionor auyhc estersfihat f hlgh Y d of Product t the aqueous solution may beused directly in the process a further bo ect to provide a new methodfor preparing of the invention allylic esters in substantially colorlessform. It I a The beta,gamma-ethylenically unsaturated halides used w toP a new andFconomlcal meihodfior in the process are those monohalideshaving a halogen Preparmg, ainyhc esters of i r w i l acldsatom attachedto a carbon atom one carbon atom re- Other ob ects and advantages of theinvention will be apmoved from the ethylenic double bonds Preferredparent from the following detailed description thereof. halides arethose of the general formula It has nowjbecn discovered that these andother objects may be accomplished by the process of the invention m R RR which comprises heating an alkali metal salt of a car- R*(ljsqllmclboxylic acid with a bcta,gamma-ethylenically unsaturated monohalide inan aqueous mediumand adding an alkaline material to the reaction mixtureso as to maintain the pI-I of the reaction mixture within the range of6.0 to 6 (often referred to as anyhc hahdes) wherein R 15 y 8.0 and thenrecovering the desired ester from the rea hyflrPcarbon radical andPreferably an alkyi action mixture. It has been found that this newprocess radical conta ningirom l to 8 carbon atoms. Examples producesthe esters in much higher yields than has been of these halide? mcludeqamong others, l' chlimde, possibleheretofore. Thus, yields obtained bythis method methanyl chlcflde, Lidwmmvpmpwe, 1 ch10") are of the orderof to while those obtained 70 p y p p y v -p s mfrom the prior methodshave ranged only from 35% to chlorophenyl 2 propcnc, and1-chloro-2-isobutyl-2-proi 60%. In addition, the esterification isaccomplished with pens. Particularly preferred are the Z-slkenylchlorides one mole of the allylic halide.

should be reacted with at least a chemical equivalent amount of thehalide. As used throughout the specificstion and claims, the expressionchemically equivalent amount" is meant the amount of the reactant neededto furnish approximately one mole of the monohalide for every sodiumatom present in the sell molecule. Thus, one of the disodium phthaleteshould be reacted with at least 2 moles of the allylic halide and onemole of the sodium allyl phthalatc should be reacted with at leastreacted with the halide in chemical equivalent ratios varyfrom 1:1 to1:5, and more preiely hom 1:1.5 to 1:3.

' Uihe reaction is conducted in an aqueous medium and preferably that inwhich the sodium salt oi the acid is formed by reacting the acid oranhydride with a oodi salt as noted above. The amount or water in thereaction mixture is preferably at least snficient to keep dium chloridein solution. 'lhis is generally accomplished by adding any to aqueousNaOl-l to the acid or anhydride to tom: the salt and then conducting thereaction in the resulting aqueous medium. As noted above, a. special andcritical feature of the process is the maintenance oi the pH of thereaction mirrture within the range of 6.0 to 3.0 during the course ofthe reaction. This is acmrnplished by measuring the pl-l oi the mixture,such as by the use of electrodes, and adding an alkaline material to thereaction in the cunt needed to keep the pH within the above-noted range.The alkaline material may be any suitable material, such as sodiumhydroxide, potassium hydroxide, sodium bicarbonate and the like, ormixtures thereof. in most cases, the amount of'alltaline material, suchas sodium hydroxide, added will generally very horn about .1 to .5illl'fii the amount of'the allylic halide present in the initial re--tional alkaline material is then added to keep the pH at the desiredlevel throughout the reaction. if the pH is not within the above range,then additional amounts should be added at the beginning to bringtheievel up to the range and then maintained there by subsequentaddilions.

The temperature employed may also vary over a. considcrable range. Thetemperature should be at least high enough to effect the reaction butshould not be above the decomposition temperature of the reactants orproducts. As a general proposition, temperatures ranging from 50 C. to200 C. can be used in the reaction, with temperatures ranging from 90 C.to 175 C. being more pr' lerred. For the preparation of the esters ofthe allylic halides and the phthalic acids, temperatures ranging fromlilt)" 'C. to 150 C. are particularly preferred. Aespheric,superatmospheric or subatmospheric pressures may be used as desired ornecessary.

v Some of the esters are easily susceptible to polymerization and inprior processes it has been desirable to employ a polymerizationinhibitor in the reaction mixture. In the present process, however, theesters are formed with out apparent loss to polymers so there is no needof adding such inhibitors to the reaction mixture.

The time of reaction will vary depending on the reactsnts andtemperature. The reaction should preferably be continued until one ofthe reactants is completely utilized. On a batch basis, the reactionshould generally not take more than 1 to 2 hours.

The esters formed in the reaction mixture may be re covered by anysuitable method, such as distillation, ou

Preferably the salts are lid ill

allyl halide is then added the mixture heated and the 9.1-

ksline materiel added to maintain the old.

The process may be conducted batchwise or in a semicontinuous orcontinuous manner as desired. The procerr is particularly adapted foruse on a continuous main ner and that is the preferred way of conductingthe process. When the process is used. to prepare the esters of phthalicacids, the process is preferably conducted by preparing a slurry of thesodium salt containing water and then adding this slurry to the reactionzone where it comes in contact and reacts with the allylic halide. Theexcess halide and other volatile components are removed overhead and aportion of the mixture taken to s seporator where it forms an aqueouslayer and organic layer. The organic layer is preferably stabilized,washed with dilute sodium hydroxide and then distilled to recover theester.

The apparatus used for the process may be constructed in any manner.When using large amounts of water, as in the above-described preferredmethod of operation, the reaction chamber as well as most of therecovery apparatus, preferably prepared from or lined with noncorrosivematerial, such as glass, platinum, gold, Hastelloy and the like.

To illustrate the manner in which the invention may be carried out, thefollowing examples are given. It is to be understood, however, that theexamples are for the ourpose or illustration and the invention is not tobe regarded as limited to any of the-specific reactants or conditionsrecited therein. Unless otherwise indicated, parts disclosed in theexamples are parts by weight.

Example i This example illustrates the unexpected improvement in yieldand quality of diallyl phthalate obtained by using the process of theinvention.

The apparatus used in this experiment was a stainless steel turbomixerheated with high pressure steam and equipped with a set of tungstensilver-silver chloride electrodes. The across the electrodes wasmeasured with a conventional potentiometer.

(a) 1.5 moles of sodium hydroxide (27% aqueous solution) and 0.75 moleof phthalic anhydride were charged to the turbomixer, stirred andcooled. 2.61 moles of allyl chloride were then added and the mixtureheated at C. for about 1.5 hours. During that time 0.47 mole of sodiumhydroxide (27% aqueous solution) was pum into the mixture at a raterequired to maintnin the pH at 6.5.

At the end of the reaction, the diallyl phthalate was recovered from thereaction mixture. This processing involved phase separation of the waterand organic phases, caustic washing of the organic phase, stabilizationof the washed organic phase containing the diallyl phthalate to a kettletemperature of about C. at 1 to 3 mm. pressure, and flash vacuumdistillation of the stabilized diallyl phthalate. 0.654 mole of diallylphthalate was recovered. This represented an 87% yield based on theanhydride charge. The diallyl phthalate recovered was almost water whiteand could be used in intended resin applications withoutfurther-purificstion to remove discoloring matter.

(b) Diallyl phthalate was prepared by a related method as in (a) abovewith the exception that no steps were taken to maintain control over thepI-l. The yield in this case was very low as noted below.

In this experiment 0.75 mole of phthalic ydride, 2.25 moles of allylchloride and 2.25 moles of sodium hydroxide were heeled roger et 123 Q.for 60 minutes. No caustic was added during the course of the reactionand the pH varied all the way from ill to 4.3. in this case, the yieldof diellyl phthalste recovered was 40% hosed on the anhydrlde charge.

(c) Experiment (a) above was repeated with the we caption that in thiscase caustic was added during the course of the reaction but the pH wasallowed to vary from 7 to 5.3. In this case, the yield of diallylphahslate Example H 2.5 moles of monoallyl phthalate and 2.5 moles ofsodium hydroxide (27% aqueous solution) were charged to the hirbominer,stirred and cooled. moles of allyl chloride were then added and themixture heated at l2tl $3. 5.0 moles of sodium bicarbonate were added soas to maintain the pH at about 6.5. At the end of the reaction, diallylphthilate was recovered as in Example 1(a). The yield of diallylphthalate recovered was 90% based on the phthalate charge. The ester wassubstantially Water white and could be used for the intendedresinappiications without further purification.

Example 1]! d0 moles of acetic acid and 8.00 moles of sodium hydroxide(27% aqueous solution) were charged to the turbornirer, stirred andcooled. 12 moles of allyl chloride were then added and the mixtureheated. at 120 C. for 90 minutes. 1.16 moles of sodium hydroxide wasadded during the course of the reaction so as to mainruin the pH at 6.5.At the end of the reaction, allyl acetate was recovered as in ExampleMa). The yield of allyl acetate was about 80% based on the acetic acidchar e. The ester was substantially water white and could be used forthe intended resin applications without lurthcr purification.

Example I V Ethyl hydrogen phthalate was made readily by drop ping ethylalcohol into an equimolar quantity of stirred molten phthaiic anhydride.0.75 mole of the ethyl hydrogcn phthalate was combined with 0.75 mole ofsodium. hydroxide (27% aqueous solution) in the turhon-liner asindicated in the preceding example. 2.6 moles of allyl chloride werethen added and the mixture heated at 120 C. for about 1 hour. Duringthat time, sodium hydroxide was added to maintain the pH at 6.5. Theallyi ethyl phthalate was recovered from the reaction mixture as shownin Example 1(a). The yield of allyl ethyl phthalate was about 30% basedon the ethyl hydrogenyhthalate charge. The ester was recovered insubstantially white form.

Example V iii ill

Example Vi 1.5 moles of a mixture of aromatic urouoesrboayllo acids.{mixture of u tert-butyl-bcmoic ocid, rh=-tert-hutyh benzoic acid,toiuic acid ohtuined us hottom uroduct from oxidation of obutyltoluene)was combined with so moles of NaOH and the mixture stirred and cooled.31? moles of allyl chloride was added to the mixture and the mixtureheated to 120 Q. for 120 minutes. Neill-l was added to maintain the gallat. about 6.5 to h. The ellyl esters were recovered as shown in lixamyleMar).

The yield of ester was 82% based on the sold charge.

pie i/l'i Example He) was repeated "with the exception that methallylchloride was employed instead of allyl chloride. Thedimethallylphthslste was also recovered in very high yield in thisprocess and was obtained in out stantially water white form.

Example l lli Example Me) is repeated with the exception that the i-tertbutylphthalic anhyclridc is employed instead of the phthalic anhydride.The diallyl d-tert-butylphthalste is recovered in high yield and insubstantially water white form.

in all of the gireceding Examples 1 to Vlll, no polymerization inhibitorwas added yet there were no apparent polymer formations. *lhe refractiveiudeu of the crude and distilled products were the same.

I claim as my invention:

1. A process for preparing an allylic ester which consists of heatingand thereby efiecting reaction between (a) a Z-alkenyl monochloride offrom 3 to it carbon atoms composed of only the chlorine, carbon. andhydro gen atoms, with (b) an alkali metal salt of an acid, said acidbeing selected from the group consisting oi lower alltanoic acids, loweralkenoic acids, lower alkanedioic acids, lower cycloalkanoic acids,benzene carlroxylic acids, and lower nlityl-s'ubstituted heuzenccarboxylic acids containing from 8 to 16 carbon atoms, with the provisothat: said benzene acids and alhyl-suhstituted acids contain up to 4carboxyl groups, said reaction being conducted in an aqueous medium andadding slimline material to maintain the pH of the reaction mixturethroughout the course of the reaction within the range of from 6.0 to

8.0, and recovering allylic ester from the reaction mixture.

2. A process as in claim 1, wherein the salt is. a sodium up to 10carbon atoms.

3. A process as in claim 1 wherein the salt and the monochloride arecombined in a mole ratio of between i about 1:2 to 1:4.

4. A process as in claim 1 wherein the salt is a disodium salt of anaromatic dicarboxylic acid.

53. A process as in claim 1 wherein the monochloride is allyl chloride.

6. A process as in claim 1 wherein acid.

7. A process for preparing diallyl ph-thalate which consists of heatingdisodium phthalate with 'allyl chloride in a. mole ratio of 1:2 to 1:4in an ac ueous' medimn and then adding alkaline material during thereaction to main tain the pH of the reaction mixture at about 6.5.

8. A process as in claim 7 wherein the alkaline material is sodiumbicarbonate.

9. A process for preparing diallyl phthalate which consists of heatingat a temperature between 3. and 200 C. a mixture containing a. disodiumsalt of phthalic acid with allyl chloride in a mole ratio of 1:2 in anaqueous medium and then adding aqueous sodium hydroxide throughout thecourse oi the reaction so as to maintain the pl-l atabout 6.5.

10. A process for preparing diullyl teuwhth which the acid is aceticcchsists of heating at a temperature between 100 C. and 200 C. a mixturecontaining a disodium salt of terephthalic acid with allyl chloride in amole) ratio of 1:2 in an acgueous mcdium and adding an alkaline matcrialthroughout the course of the reaction so as to maintain the pH at about6.5.

11. A process fer preparing diallyl isophthalatc which consists c5heating at a temperature betwcen 100" C. and

200 C. sadium salt of isophthalic acid with allyl chloride in a molt:ratio of 1:2 in an aqueous medium and adding an alkaline materialthroughout the course of the reaction so as ta msintain the pH at about6.5.

12. A process fur preparing allyl acetate which consists of heating =21a temperature between 100 C. and 200 C. sodium acetate with ally}chlcride in a mole ratio of ahcmt 2:2 in an aqueous mcdium anti addingNaOH to the mixture to maintain the pH at about 6.5 throughout theccurse of the reacticm.

Reficrences Cited in thc file cf this patent UNITED STATES PATENTS2,207,613 Coleman et a1. -Tilly 9, 1940 2,275,466 Pollack et al. Mar.10, 1942 2,275,467 Pollack ct al. Mar. 10, 1942 2,296,823 1 Pollack et aSept. 22, 1942 OTHER REFERENCES Fieser etaln "Organic Chemistry, pp.343, 649, Reinhcld, 1956.

Gilman: Organic Chemistry," vol. 1, p. 1004 to1005, 1013 t0 1019, I.Wiley, 1943.

1. A PROCESS FOR PREPARING AN ALLYLIC ESTER WHICH CONSISTS OF HEATINGAND THEREBY EFFECTING REACTION BETWEEN (A) A 2-ALKENYL MONOCHLORIDE OFFROM 3 TO 10 CARBON ATOMS COMPOSED OF ONLY THE CHLORINE, CARBON ANDHYDROGEN ATOMS, WITH (B) AN ALKALI METAL SALT OF AN ACID, SAID ACIDBEING SELECTED FROM THE GROUP CONSISTING OF LOWER ALKANOIC ACIDS, LOWERALKENOIC ACIDS, LOWER ALKANEDIOIC ACIDS, LOWER CYCLOALKANOIC ACIDS,BENZENE CARBOXYLIC ACIDS, AND LOWER ALKYL-SUBSTITUTED BENZENE CARBOXYLICACIDS CONTAINING FROM 8 TO 16 CARBON ATOMS, WITH THE PROVISO THAT SAIDBENZENE ACIDS AND ALKYL-SUBSTITUTED ACIDS CONTAIN UP TO 4 CARBOXYLGROUPS, SAID REACTION BEING CONDUCTED IN AN AQUEOUS MEDIUM AND ADDINGALKALINE MATERIAL TO MAINTAIN THE PH OF THE REACTION MIXTURE THROUGHOUTTHE COURSE OF THE REACTION WITHIN THE RANGE OF FROM 6.0 TO 8.0, ANDRECOVERING ALLYLIC ESTER FROM THE REACTION MIXTURE.